diff options
Diffstat (limited to 'sys/netinet6/in6_gif.c')
| -rw-r--r-- | sys/netinet6/in6_gif.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/sys/netinet6/in6_gif.c b/sys/netinet6/in6_gif.c index d476829e8e3b..2bab1c57ce2a 100644 --- a/sys/netinet6/in6_gif.c +++ b/sys/netinet6/in6_gif.c @@ -194,6 +194,11 @@ in6_gif_setopts(struct gif_softc *sc, u_int options) sc->gif_options = options; in6_gif_attach(sc); } + + if ((options & GIF_NOCLAMP) != + (sc->gif_options & GIF_NOCLAMP)) { + sc->gif_options = options; + } return (0); } @@ -289,6 +294,7 @@ in6_gif_output(struct ifnet *ifp, struct mbuf *m, int proto, uint8_t ecn) { struct gif_softc *sc = ifp->if_softc; struct ip6_hdr *ip6; + u_long mtu; /* prepend new IP header */ NET_EPOCH_ASSERT(); @@ -304,11 +310,15 @@ in6_gif_output(struct ifnet *ifp, struct mbuf *m, int proto, uint8_t ecn) ip6->ip6_nxt = proto; ip6->ip6_hlim = V_ip6_gif_hlim; /* - * force fragmentation to minimum MTU, to avoid path MTU discovery. - * it is too painful to ask for resend of inner packet, to achieve - * path MTU discovery for encapsulated packets. + * Enforce fragmentation to minimum MTU, even if the interface MTU + * is larger, to avoid path MTU discovery when NOCLAMP is not + * set (default). IPv6 does not allow fragmentation on intermediate + * router nodes, so it is too painful to ask for resend of inner + * packet, to achieve path MTU discovery for encapsulated packets. */ - return (ip6_output(m, 0, NULL, IPV6_MINMTU, 0, NULL, NULL)); + mtu = ((sc->gif_options & GIF_NOCLAMP) == 0) ? IPV6_MINMTU : 0; + + return (ip6_output(m, 0, NULL, mtu, 0, NULL, NULL)); } static int |